Washing soda (Na2CO3·10H2O) is obtained from which compound in the Solvay process?

Washing soda (Na2CO3·10H2O) is obtained from sodium bicarbonate in the Solvay process. Sodium bicarbonate is then heated to form sodium carbonate (Na2CO3), which is converted to washing soda by adding water of crystallization. In the Solvay process, sodium carbonate is produced using sodium chloride and limestone. Washing soda is a crystalline, white, water-soluble solid that has many household and industrial uses.